Diabetologia

, Volume 52, Issue 12, pp 2499–2506

Combined randomised controlled trial experience of malignancies in studies using insulin glargine

Open Access
Article

DOI: 10.1007/s00125-009-1530-5

Cite this article as:
Home, P.D. & Lagarenne, P. Diabetologia (2009) 52: 2499. doi:10.1007/s00125-009-1530-5

Abstract

Aims/hypothesis

Recent publications of data extracted from population registries have suggested a possible relationship between treatment with insulin glargine and increased incidence of cancer/breast cancer. The aim of the present study was investigate this possible relationship using data from the manufacturer’s (sanofi-aventis) pharmacovigilance database.

Methods

We analysed the manufacturer’s (sanofi-aventis) pharmacovigilance database for all randomised clinical trials (RCTs; Phase 2–4) comparing insulin glargine with any comparator in type 1 or type 2 diabetes. We identified all serious adverse events coded under the System Organ Class of ‘neoplasms, benign, malignant and unspecified’. Treatment-emergent neoplasms judged to be malignant were included in this analysis.

Results

The database included 31 studies, 12 in type 1 diabetes and 19 in type 2 diabetes. Twenty compared insulin glargine with NPH insulin, 29 were parallel-group studies and two had a crossover design. Studies were generally of 6 months’ duration, except for trial reference number 4016 (n = 1,017), which had a duration of 5 years. Overall, 10,880 people were included in the analysis (insulin glargine, 5,657; comparator, 5,223). Forty-five people (0.8%) vs 46 people (0.9%) reported 52 and 48 cases of malignant cancer in the insulin glargine and comparator groups, respectively (RR 0.90, 95% CI 0.60–1.36). Skin (12 people with 16 events vs six people with seven events, RR 1.85, 95% CI 0.69–4.92), colon and rectum (six vs ten people, RR 0.55, 95% CI 0.20–1.52), breast (four vs six people, RR 0.62, 95% CI 0.17–2.18) and gastrointestinal tract (six vs four people, RR 1.38, 95% CI 0.39–4.90) were the most commonly reported sites.

Conclusions/interpretation

In these 31 RCTs, insulin glargine was not associated with an increased incidence of cancer, including breast cancer, compared with the comparator group.

Keywords

Cancer Diabetes mellitus Insulin analogues Insulin glargine 

Abbreviations

ICH

International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use

RCT

randomised clinical trial

SEER

Surveillance, Epidemiology and End Results

Introduction

Recent publications of data extracts from population registries have triggered debate about a potential relationship between treatment with insulin glargine (A21Gly,B31Arg,B32Arg human insulin) and an increased incidence of cancer or breast cancer [1, 2, 3, 4]. Here, we fulfil an obligation to report the evidence from randomised clinical trials (RCTs) within the manufacturer’s database.

All RCTs sponsored by sanofi-aventis that compared the use of insulin glargine with another active comparator in either type 1 or type 2 diabetes and had a treatment duration of at least 4 weeks were included in this analysis. These studies included people with either type 1 or type 2 diabetes, and were either part of the initial development plan for the registration of the product (Phase 2 and 3) or conducted after the commercial launch of insulin glargine (Phase 4 studies).

Methods

As it is obligatory for all sponsored trials routinely to report serious adverse events to the manufacturer, and as the manufacturer has a database of such studies, no literature search was performed. Only RCTs that compared insulin glargine with an active comparator and that had a final clinical study report available for review on 15 May 2009 were included in this analysis.

Studies and ascertainment of malignancy

A thorough review of the sanofi-aventis safety database for the identified studies was performed to assess the incidence of any malignancies that led to reports of serious adverse events during the conduct of the trials. All RCTs of insulin glargine were included. All serious adverse events coded in the Medical Dictionary for Regulatory Activities (MedDRA) System Organ Class of neoplasms—benign, malignant and unspecified—were included in the evaluation [5]. An adverse event is classified as serious if it fulfils the criteria set down by the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), that is if it: is life-threatening or results in death; requires inpatient hospitalisation or prolongation of existing hospitalisation; results in persistent or significant disability/incapacity; is a congenital anomaly/birth defect; or is another ‘medically important’ event that may jeopardise the study participant or may require intervention to prevent one of the other outcomes listed in the definition above [6]. The ICH recommends that cancers are characterised as ‘medically important’ adverse events and, therefore, are classified as serious adverse events [6].

All such identified records in the sanofi-aventis pharmacovigilance database were reviewed, by treatment, by the manufacturer’s drug safety personnel with experience of adverse event reporting, and only treatment-emergent neoplasms judged to be malignant were included, independent of treatment group. Each person was counted only once, although separate counts for people and cases are provided if more than one malignancy was reported in the same person. Relative risks and 95% confidence intervals were calculated for insulin glargine relative to the comparator for the total incidence of malignancies and for individual classifications using all identified RCTs in type 1 and type 2 diabetes combined.

Results

The Clintrace sanofi-aventis safety database contains 31 eligible studies. Twelve studies were performed in people with type 1 diabetes and 19 studies in people with type 2 diabetes; most of the studies compared insulin glargine with NPH insulin (20 studies). Nearly all (29) were parallel-group trials (two had a crossover design). Details of these studies are summarised in Table 1. Most studies were open label, 19 were of around 6 months in duration, with six of longer duration, notably the retinopathy study 4016, which had a duration of 5 years [7].
Table 1

Details of the studies included in the analysis

Trial number (reference)

Comparator

Study duration (weeks)

Participants randomised and treated (insulin glargine/control arm)

Type 1 diabetes

 2002 [15]

NPH

4

168/88

 2003 [16]

NPH

4

223/110

 3001 [17]

NPH

28

292/293

 3003 [18]

NPH

28

174/175

 3004 [19]

NPH

28

264/270

 3005 [20]

NPH

16

310/309

 4003a

Ultralente

6–7

29/27

 4005 [21]

NPH

32

26/25

 4006 [22]

NPH

32

53/52

 4010 [23]

NPH

30

62/63

 4030 [24]

NPH or lente

24

85/90

 4036 [25]

Insulin lispro as CSII

24

26/24

Type 2 diabetes

 2004 [26]

NPH

4

136/68

 2006a

 ‘Conventional insulin’

4

57/57

 3002 [27]

NPH

52

289/281

 3006 [28]

NPH

28

259/259

 3102a

NPH

28

158/159

 3502 [29]

OGLDs

24

203/197

 4001 [30]

NPH

28

464/233

 4002 [31]

NPH

24

367/389

 4012 [32]

NPH

24

221/223

 4013 [33]

NPH

28

231/250

 4014 [34]

Rosiglitazone

24

105/112

 4016 [7, 8]

NPH

5 years

514/503

 4020a

Pioglitazone

48

164/181

 4021a

Insulin lispro 25%, insulin lispro protamine 75%, mix

24

113/99

 4022a

OGLDs

48

118/130

 4027 [35]

NPH 30/70

28

177/187

 4040 [36]

Insulin lispro

44

205/212

 4042 [37]

OGLDs and dietary measures

40

103/108

 6001 [38]

NPH

36

61/49

aData available from sanofi-aventis on request

CSII, continuous subcutaneous insulin infusion (of insulin lispro [B28Lys,B29Pro human insulin]); OGLDs, oral glucose-lowering drugs

Overall, 10,880 people were included in the analysis, with 5,657 people randomised to insulin glargine and 5,223 people randomised to the comparator, representing a total follow-up time of 4,711 and 4,524 person-years, respectively. Baseline characteristics of the participants were comparable between treatment groups (Table 2).
Table 2

Participant characteristics in the studies identified for inclusion in the analysis

Trial number

Age (years)

Sex ratio M/F

BMI (kg/m2)

Duration of diabetes (years)

Baseline HbA1c (%)

Insulin glargine

Comparator

Insulin glargine

Comparator

Insulin glargine

Comparator

Insulin glargine

Comparator

Insulin glargine

Comparator

Type 1 diabetes

 2002a

37.3

37.9

51.2/48.8

53.4/46.6

24.2

24.5

16.3

16.3

7.9

7.9

 2003a

36.6

35.7

60.5/39.5

61.8/38.2

24.0

24.0

9.5

11.0

8.0

7.8

 3001

39.4 (12.8)

39.0 (11.7)

54.8/45.2

56.7/43.3

24.6 (3.2)

25.1 (3.3)

15.9 (11.5)

15.2 (9.4)

7.9 (1.2)

8.0 (1.2)

 3003

11.8 (2.5)

11.5 (2.4)

55.7/44.3

48.0/52.0

18.8 (2.8)

18.9 (2.9)

5.0 (3.0)

4.7 (3.1)

8.5 (1.3)

8.9 (1.6)

 3004

38.2 (12.2)

38.9 (11.9)

53.4/46.6

47.8/52.2

25.6 (4.0)

25.9 (4.6)

17.9 (11.7)

16.9 (10.0)

7.7 (1.2)

7.7 (1.1)

 3005

38.9 (12.2)

39.5 (12.2)

48.7/51.3

52.4/ 47.6

25.5 (3.4)

25.7 (3.9)

18.7 (11.5)

18.4 (11.8)

7.6 (1.2)

7.7 (1.2)

 4003

36.4 (9.2)

37.4 (9.2)

45.0/55.0

26.0/74.0

26.3 (3.5)

25.2 (3.1)

N/A

N/A

N/A

N/A

 4005

15.1 (1.7)

14.5 (1.6)

46.2/53.8

38.5/61.5

23.3 (4.1)

23.0 (3.8)

6.1 (3.6)

8.0 (3.3)

9.4 (1.1)

9.1 (1.4)

 4006

41.1 (13.9)

41.1 (10.7)

32.0/68.0

41.4/58.6

26.5 (2.8)

25.4 (3.0)

22.4 (15.1)

20.8 (11.3)

8.1 (0.8)

7.9 (0.8)

 4010

41.7 (12.9)

39.3 (13.9)

38.7/61.3

39.7/60.3

27.0 (3.6)

26.0 (3.9)

17.9 (10.5)

17.1 (9.7)

9.2 (1.1)

9.7 (1.3)

 4030

13.1 (2.4)

13.3 (2.5)

45.9/54.1

45.6/54.4

22.7 (3.8)

22.7 (5.0)

5.1 (3.4)

5.4 (3.7)

7.8 (0.8)

8.0 (0.8)

 4036

42.4 (9.9)

 37.6 (12.3)

 53.8/46.2

 54.2/45.8

 24.3 (1.9)

 23.8 (2.7)

 20.9 (10.6)

 18.5 (8.4)

 7.8 (0.6)

 7.7 (0.7)

Type 2 diabetes

 2006

60.9 (10.8)

60.5 (9.8)

59.6/40.4

59.6/40.4

27.0 (2.9)

26.3 (3.3)

13.4 (8.2)

13.8 (8.6)

9.3 (1.1)

9.6 (1.2)

 2004a

59.5

59.2

61/39

57.4/42.6

27.2

27.7

9.7

9.1

9.7 (1.3)

9.5 (1.4)

 3002

59.6 (9.3)

59.4 (9.1)

53.3/46.7

54.1/45.9

29.3 (4.3)

28.8 (4.3)

10.2 (6.2)

10.5 (6.0)

9.0 (1.2)

8.9 (1.1)

 3006

59.5 (9.7)

59.2 (9.9)

57.9/42.1

62.2/37.8

30.7 (5.0)

30.4 (5.1)

13.4 (8.3)

14.1 (9.0)

8.6 (1.2)

8.5 (1.2)

 3102b

9.1 (1.1)

9.1 (1.0)

 3502

56.2 (9.3)

56.8 (10.0)

66.5/33.5

63.7/36.3

31.2 (4.5)

31.4 (4.6)

7.7 (5.5)

8.2 (6.5)

8.6 (1.1)

8.5 (1.0)

8.6 (0.1)c

8.6 (0.1)c

 4001

60.3 (9.2)

61.8 (8.5)

54.9/45.1

51.3/48.7

28.7 (4.2)

28.9 (3.9)

10.2 (7.0)

9.9 (6.0)

8.9 (0.8)

8.9 (0.8)

 4002

54.7 (9.5)

55.6 (8.9)

55/45

56.3/43.7

32.5 (4.6)

32.2 (4.8)

8.4 (5.6)

9.0 (5.6)

8.6 (0.9)

8.6 (0.9)

 4012

55.4 (8.4)

56.3 (8.4)

39.4/60.6

43.8/56.2

24.8 (3.0)

25.1 (3.1)

10.3 (6.2)

10.0 (5.2)

9.0 (0.9)

9.1 (0.9)

 4013

56.1 (9.9)

57.1 (9.6)

42.9/57.1

38.0/62.0

27.3 (3.7)

27.2 (4.0)

10.3 (6.4)

10.8 (6.4)

9.0 (1.0)

9.2 (0.9)

 4014

55.9 (10.5)

55.3 (11.4)

45.2/54.8

58/42

34.6 (7.0)

33.6 (6.3)

8.5 (5.8)

8.1 (5.1)

8.8 (1.0)

8.7 (1.0)

 4016

54.9 (8.8)

55.3 (8.5)

54.2/45.8

53.6/46.4

34.5 (7.2)

34.1 (7.2)

10.7 (6.9)

10.8 (6.7)

8.4 (1.4)

8.3 (1.4)

 4020

52.5 (11.0)

51.8 (10.3)

48/52

49.6/50.4

33.6 (7.0)

33.6 (7.3)

6.4 (4.9)

5.8 (4.2)

9.4 (1.2)c

9.4 (1.3)c

 4021

54.2 (10.5)

52.8 (9.8)

47.8/52.2

45.5/54.5

33.4 (5.2)

33.5 (6.2)

10.1 (7.0)

8.9 (6.6)

9.1 (0.9)

9.0 (0.9)

 4022

53.6 (9.7)

52.1 (10.3)

47.5/52.5

48.5/51.5

34.5 (7.0)

35.2 (7.4)

7.5 (4.5)

7.6 (6.0)

9.0 (1.2)

9.0 (1.2)

 4027

60.9 (8.7)

60.4 (9.1)

61.0/39.0

57.0/43.0

29.5 (3.6)

29.6 (3.6)

9.9 (7.3)

9.9 (6.4)

8.9 (1.0)

8.9 (0.9)

 4040

60.0 (9.0)

59.7 (9.0)

52.5/47.6

58.7/41.4

29.2 (3.7)

29.4 (3.5)

9.0 (6.8)

8.5 (6.1)

8.7 (1.0)

8.7 (1.0)

 4042

60.6 (7.7)

60.7 (8.1)

55.3/44.7

50.0/50.0

30.1 (3.5)

29.8 (3.4)

10.0 (6.2)

10.1 (6.9)

7.6 (0.3)

7.5 (0.4)

 6001

56.1 (9.4)

57.5 (8.5)

62/38

65/35

31.3 (5.3)

32.1 (5.4)

8.6 (4.3)

8.5 (4.8)

9.1 (1.2)

9.3 (1.1)

Data are means (SD) unless otherwise indicated

aSDs for trials 2002, 2003 and 2004 are unavailable in source documents

bData for trial number 3102 are unavailable

cAdjusted mean (SEM)

N/A, not applicable

Overall, there was no difference in the incidence of malignancies between insulin glargine-treated people and the comparator group (Table 3), with 52 cases of malignant cancer documented as a serious treatment-emergent event in 45 people in the insulin glargine group (0.8%) and 48 cases in 46 people in the comparator group (0.9%). Among such malignancies, most occurred in people with type 2 diabetes, with 45 cases in 39 people in the insulin glargine group (1.0%) and 46 cases in 44 people in the comparator group (1.2%).
Table 3

All malignant neoplasms reported in controlled clinical trials comparing insulin glargine with a comparator (participants evaluable for safety)

Trial duration

Insulin glargine

Comparator

No. of patients

All malignancies

Breast cancer

No. of patients

All malignancies

Breast cancer

 

No. affected (%) [no. of events]

No. affected (%) [no. of events]

No. affected (%) [no. of events]

No. affected (%) [no. of events]

Type 1 diabetes (12 trials): insulin glargine vs other basal insulin

 3001

292

2 (0.7) [2]

0

293

0

0

 3004

264

3 (1.1) [3]

1 (0.4) [1]

270

0

0

 3005

310

1 (0.3) [2]

0

309

2 (0.6) [2]

0

 2002

168

0

0

88

0

0

 2003

223

0

0

110

0

0

 3003

174

0

0

175

0

0

 4003

29

0

0

27

0

0

 4005

26

0

0

25

0

0

 4006

53

0

0

52

0

0

 4010

62

0

0

63

0

0

 4030

85

0

0

90

0

0

 4036

26

0

0

24

0

0

 Total type 1

1,712

6 (0.4) [7]

1 (0.1) [1]

1,526

2 (0.1) [2]

0

Type 2 diabetes: insulin glargine vs NPH insulin ≤1 year in duration (ten trials)a

 3002

289

3 (1.0) [3]

0

281

7 (2.5) [7]

1 (0.4) [1]

 3006

259

6 (2.3) [8]

0

259

3 (1.2) [4]

0

 3102

158

1 (0.6) [1]

0

159

1 (0.6) [1]

0

 4001

464

3 (0.6) [3]

0

233

1 (0.4) [1]

0

 4002

367

0

0

389

1 (0.3) [1]

1 (0.3) [1]

 2004

136

0

0

68

0

0

 4012

221

0

0

223

0

0

 4013

231

0

0

250

0

0

 4027

177

0

0

187

0

0

 6001

61

0

0

49

0

0

 Total

2,363

13 (0.6) [15]

0

2,098

13 (0.6) [14]

2 (0.1) [2]

Type 2 diabetes: insulin glargine vs NPH insulin >1 year in duration (one trial)

 4016

514

20 (3.9) [23]

3 (0.6) [3]

503

31 (6.2) [32]

4 (0.8)b

Type 2 diabetes: insulin glargine vs oral agents (five trials)

 3502

203

1 (0.5) [1]

0

197

0

0

 4014

105

0

0

112

0

0

 4020

164

0

0

181

0

0

 4022

118

0

0

130

0

0

 4042

103

2 (1.9) [2]

0

108

0

0

 Total

693

3 (0.4) [3]

0

728

0

0

Type 2 diabetes: insulin glargine vs other insulin than NPH (three trials)

 2006

57

1 (1.8) [1]

0

57

0

0

 4021

113

0

0

99

0

0

 4040

205

2 (1.0) [3]

0

212

0

0

 Total

375

3 (0.8) [4]

0

368

0

0

 Total type 2 diabetes

3,945

39 (1.0) [45]

3 (0.1) [3]

3,697

44 (1.2) [46]

6 (0.2) [6]

 Grand total

5,657

45 (0.8) [52]

4 (0.1) [4]

5,223

46 (0.9) [48]

6 (0.1) [6]

aOne study used NPH premixed insulin (4027)

bIncludes one recurrent breast cancer; in addition, there was one case of breast cancer present at baseline that was not considered treatment emergent

The corresponding RR for malignant cancer with insulin glargine compared with the comparator is 0.90 (95% CI 0.60–1.36).

Four cases of malignant breast cancer were reported in the insulin glargine group (0.1%) and six cases in the control group (0.1%). The RR for breast cancer is 0.62 (95% CI 0.17–2.18).

These data were primarily driven by the findings in the 5 year RCT (study 4016) that compared insulin glargine (n = 514) with NPH insulin (n = 503) in people with type 2 diabetes who were randomised and received treatment [7, 8]. In that study, the overall number of people with neoplasms was similar in the insulin glargine and NPH insulin groups (57 [11.1%] and 62 [12.3%] people, respectively) [8]. When considering only the number of people in the retinopathy study with malignant neoplasms reported as serious treatment-emergent events, the rate was also similar in both groups (insulin glargine vs NPH insulin, 23 cases in 20 people [3.9%] vs 32 cases in 31 people [6.2%]). Finally, the number of people with breast cancer reported as a serious adverse event in that study was similar between the two treatment groups (three [0.6%] vs four [0.8%] cases – there was also an additional fifth case in the NPH insulin group, although this was reported as a non-serious adverse event).

Table 4 summarises the sites of all malignancies in the pooled studies comparing insulin glargine with comparator. The most frequently reported site (insulin glargine vs comparator) included the skin (16 events in 12 people [0.2%] vs seven events in six [0.1%] people, RR 1.85, 95% CI 0.69–4.92), colon and rectum (six [0.1%] vs ten [0.2%], RR 0.55, 95% CI 0.20–1.52), breast (four [0.1%] vs six [0.1%], RR 0.62, 95% CI 0.17–2.18) and gastrointestinal tract (six [0.1%] vs four [0.1%], RR 1.38; 95% CI 0.39–4.90).
Table 4

Location of malignancies in randomised controlled studies of insulin glargine

Classification

No. using insulin glargine (%) [no. of events]

No. in the control group (%) [no. of events]

Relative risk (95% CI)

Total number of people

5,657 (100) [52]

5,223 (100) [48]

Blood

2 (0.04) [2]

1 (0.02) [1]

1.85 ( 0.17–20.36)

Vertebral body

1 (0.02) [1]

0

Breast

4 (0.07) [4]

6 (0.11) [6]

0.62 (0.17–2.18)

Nasal

1 (0.02) [1]

0

Lung

3 (0.05) [3]

3 (0.06) [3]

0.92 (0.19–4.57)

Gastrointestinal (not otherwise stated)

6 (0.11) [6]

4 (0.08) [4]

1.38 (0.39–4.90)

Colon and rectum

6 (0.11) [6]

10 (0.19) [10]

0.55 (0.20–1.52)

Hepatic and biliary

2 (0.04) [2]

3 (0.06) [3]

0.62 (0.10–3.68)

Pancreas

3 (0.05) [3]

3 (0.06) [3]a

0.92 (0.19–4.57)

Renal

3 (0.05) [3]

0

Prostate

1 (0.02) [1]

3 (0.06) [3]

0.31 (0.03–2.96)

Bladder

0

2 (0.04) [2]

Genitourinary

3 (0.05) [3]

4 (0.08) [4]

0.69 (0.16–3.09)

Thyroid

2 (0.04) [2]

0

Endocrine

0

1 (0.02) [1]

Neurological

0

2 (0.04) [2]

Skin

12 (0.21) [16]

6 (0.11) [7]

1.85 (0.69–4.92)

Total number of people with malignanciesb

45 (0.80) [52]

46 (0.88) [48]

0.90 (0.60–1.36)

aIncludes one pancreatic carcinoma from study 3005 that was erroneously reported as a non-serious adverse event

bThe sum of each location of malignancies differs slightly from the total number owing to the fact that individuals could have malignancies in more than one location or more than one preferred term may be associated with a malignancy

With respect to the type of malignancy, at least two more tumours were reported in the comparator group vs the insulin glargine group for the following classifications: colon and rectum (ten [0.2%] vs six [0.1%]), prostate (three [0.1%] vs one [0.0%]), neurological (two [0.0%] vs zero [0.0%]) and bladder (two [0.0%] vs zero [0.0%]). Conversely, there were nine more cases of skin cancer in the insulin glargine group compared with the comparator group (16 cases in 12 people [0.2%] vs seven cases in six people [0.1%]), including an imbalance of six (0.1%) to one (0.0%) for malignant melanoma. However, in the 5 year Study 4016, the incidence of all melanomas (documented as serious and non-serious adverse events) was not different between treatment groups (three each, with one case in the comparator [NPH insulin] group and two in the insulin glargine group reported as serious adverse events).

Within the sanofi-aventis safety database, in addition to the RCTs, there are 26 completed uncontrolled studies with insulin glargine, involving a total of 68,201 participants with type 1 or type 2 diabetes treated for up to 3 years. The data from these 26 uncontrolled studies represent a total follow-up time of 22,074 person-years for insulin glargine treatment.

In total, there were 111 cases of malignancy, including nine cases of breast cancer, reported in these studies. The overall cancer rate is estimated to be 5.0 cases per 1,000 person-years (111 out of 22,074 person-years) and the breast cancer rate is estimated to be 82 cases per 100,000 person-years (that is, nine out of 11,027 person-years—the denominator here being the exposure of women in the type 2 diabetes RCTs). In investigator-sponsored trials and product registries (intensified monitoring) for which no enrolment figures are available, the sanofi-aventis safety database contains an additional 75 individuals with malignancies, including nine cases of breast cancer.

Discussion

Based on our analysis of 31 RCTs, insulin glargine was not associated with an increased incidence of cancer, including breast cancer, when compared with the control/comparator group.

The overall incidence of cancer in the trials included in this analysis was lower in people with type 1 diabetes than in those with type 2 diabetes, perhaps because the former were younger and less obese than the people with type 2 diabetes (Table 2), and were exposed for a shorter time. Obesity increases the risk of colon cancer by as much as 1.5- to 2-fold and accounts for up to 35% of the total incidence of colon cancer [9]. In terms of age, the prevalence of cancer increases with increasing age and peaks in people aged 75 years or older [10, 11]. People with type 2 diabetes in this analysis were typically in their mid to late fifties and, thus, the majority were at an age associated with greater risk for cancer compared with the people with type 1 diabetes.

The results presented are based on formal RCTs, which represent level 1—the highest level—of evidence-based study design. Another advantage of the present analysis is that the clinical trials database reviewed here included a large number of people (n = 10,880), allowing the opportunity to identify rarer adverse events. Furthermore, the events were recorded reasonably accurately, as in any RCT, as the monitoring of adverse events followed the rules of good clinical practice and international pharmacovigilance regulations [12]. Finally, our analysis included one long-term 5 year controlled study that showed comparably reassuring findings, with no differences in the incidence of cancers between patients treated with insulin glargine and patients treated with NPH insulin.

Nevertheless, this analysis must be considered in light of some limitations. The duration of most of the studies was relatively short (mostly 6 months) and does not reflect the lifetime risk for cancer, while only one study was longer than 1 year. Nevertheless, if growth promotion is postulated as the mechanism of any increased cancer risk, it would appear early in the use of any therapeutic entity. None of the RCTs was specifically designed to evaluate the risk of cancer with insulin glargine, although all had mandatory reporting of adverse events, including treatment-emergent neoplasms. Randomised controlled trials may not fully reflect real-life clinical practice; investigators may, for example, be less likely to include people with previous malignancies. People using thiazolidinediones, which have been suggested as protective against breast or pancreatic cancer [13, 14] and linked with increases in bladder cancer, [13] were often not included in the insulin studies, owing to the relative or absolute labelling restrictions in participating countries. Finally, the number of malignancies reported here may differ slightly from the published numbers for each study owing to differences in reporting methods; for example, only cases classified as serious treatment-emergent events were included in this analysis, whereas the original publications may have included cases classified as non-serious or serious. In addition, we only included treatment-emergent cases, whereas some of the publications may have included pre-existing cases.

However, analysis of the 26 uncontrolled trials with insulin glargine shows that the overall cancer rate is estimated to be 5.0 cases per 1,000 person-years. Compared with the age-adjusted incidence rate of 4.63 per 1,000 per year in the USA (based on cases diagnosed in 2002–2006 from 17 geographic areas included in the Surveillance, Epidemiology and End Results [SEER] programme), there was no indication of increased cancer risk in people with diabetes using insulin glargine. However, we acknowledge that under-reporting of cancer events can occur in uncontrolled observational studies, where follow-up with physicians is not always possible and, therefore, these results should be interpreted with caution.

For breast cancer, the incidence rate in women participating in non-interventional trials of insulin glargine may be estimated to be 82 cases per 100,000 person-years. Compared with the incidence rate of 124 per 100,000 women per year in the US SEER database, no safety signal for breast cancer was identified with the use of insulin glargine in these clinical trials.

In conclusion, these data suggest that insulin glargine is not associated with an increased risk of cancer compared with the different comparators (mainly NPH insulin). While the data provide useful reassuring and contributory information regarding the safety of insulin glargine, they underscore the importance of continued long-term follow up of participants in clinical trials.

Acknowledgements

This analysis was sponsored by sanofi-aventis. Editorial support was provided through the Global Publications Group of sanofi-aventis.

Role of the funding source

The sponsor undertook the review of the pharmacovigilance database, collected and managed the data and undertook the statistical analyses. The corresponding author had full access to the data, and both authors made the decision to submit for publication.

Duality of interest

Institutions connected with P. D. Home receive funding from sanofi-aventis and other insulin analogue manufacturers in regard of his advisory, educational and research activities, including with insulin glargine. P. Lagarenne is an employee of sanofi-aventis.

Open Access

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Copyright information

© The Author(s) 2009

Authors and Affiliations

  1. 1.ICM-Diabetes, The Medical SchoolNewcastle UniversityNewcastle upon TyneUK
  2. 2.Pharmacovigilance & Epidemiologysanofi-aventisBridgewaterUSA

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